CONJUGATION OF CATALASE TO A CARRIER ANTIBODY VIA A STREPTAVIDIN-BIOTIN CROSS-LINKER

Targeting of catalase could be useful in antioxidative protection of c ells challenged with H2O2. In the present study we conjugated catalase to a carrier model antibody using a biotin-streptavidin (SA) cross-li nker and characterized the functional activity of the conjugate. Neith er biotinylation nor conjugation with SA decreased the enzymic activit y of catalase. Further coupling of radiolabelled biotinylated catalase (b-catalase) to biotinylated antibody (b-Ab) via SA using a two-step conjugation procedure did not change enzymic activity of b-catalase. b -Ab-SA-b-catalase specifically bound to antigen-coated plastic wells, but not to albumin-coated plastic wells. Substitution of b-Ab with con trol biotinylated IgG (b-IgG) abrogated binding of the catalase to the antigen. H2O2 was degraded in antigen-coated wells preincubated with b-Ab-SA-b-catalase, but not with b-IgG-SA-b-catalase. Thus b-Ab-SA-b-c atalase specifically binds to immobilized antigen and degrades H2O2 af ter binding to the target. The methodology described in the present pa per may be useful for the development of a novel strategy for antioxid ant therapy.